Hey @Iws!
The prefixes are created when you install Wordpress, if you are migrating, it carries the prefixes where the site goes. Changing it on the wp-config.php will only make Wordpress look for the wrong prefix, to change it for real you need to change the prefixes on the tables in the database and the line on wp-config.
The best and easiest way to migrate a website developed in Local would be indeed to use Duplicator or All-in-One WP Migration. The process of Duplicator is described in the video on the link below:
As for other workflows of migrating your site, you can find it on the Workflow topic: